DETERMINISTIC SEISMIC HAZARD EVALUATION FOR THE CITY OF DUZCE

The main goal of the study is to define thedesign input motion scenarios for the future microzonation study. The study ofthe “Earthquake hazard Assessment in Duzce” is performed for the seismic hazardfor the city of Duzce in order to get the design ground motion parameters forthe next microzonation study. The main goal of the present study is to givebriefly the steps and the uncertainties derived from the performing deterministicseismic hazard study for the city of Duzce based exclusively on the existingdata and the seismicity of the region. This study uses all available sources ofinformation, technical papers and research works performed so far. Theseismotectonic environment of the area is very active, however there arecertain uncertainties (to our knowledge) regarding the characteristic of theseismic source zones, the fault length, the magnitudes assigned to the faults,the seismicity parameters, the seismic history of the area, the attenuationrelationships etc. During the few past years several research studies havecontributed in better understanding the seismotectonic and geologicalbackground of the region. There are still a lot of parameters which are poorlyknown in order to provide more reliable seismological information of the area. Seismic hazard in Duzcewas performed usinguniform seismic zones (USZ). The seismic hazard was performed using apoisoning approach for mean return periods of 100 and 475 years. In the Seismotectoniczonation criteria; the seismicsources selected to perform a seismic hazard analysis were determined byKayabali K (2002). In total 14 seismicsources were delineated in Turkey based mostly on Erdik et al (1985) andYaltirak et al (1998) works. As a result, we have computed the PGA values and the accelerationresponse spectra for soft soil and rock (considered as outcrop) conditions inDuzce and for two mean return periods. In addition, several other comparisonswith real records of previous earthquakes and seismic hazard studies willenhance the reliability of the obtained results. The design PGA value for rock(or outcrop) conditions and for 250 years return period is most probablybetween 0.3g and 0.35g. For 475 years return period it will be almost thedouble of it (we could accept in a reasonable way a PGA = 0.60g). These valueswill be further validated and then will be used, as incident peak groundaccelerations, of a uniform incident ground motion, at the bedrock basement ofDuzce for the detailed microzonation study of Duzce.